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Re: st: set memory question


From   David Airey <david.airey@Vanderbilt.Edu>
To   Statalist <statalist@hsphsun2.harvard.edu>
Subject   Re: st: set memory question
Date   Wed, 26 Aug 2009 13:57:11 -0500

.

Thanks Eric. Stata tech support (thanks Kerry) had a similar answer. Time to buy more memory I think.


"If you would like to get a good idea of when your system is beginning to use
virtual memory with Stata then you should specify a very small swap file
(enough to contain everything currently running) and then when the operating system starts complaining about allocating RAM you will have reached the limit. Another method to try is to check the machine's hard drive light and see if it
goes from the normal flicker to a steady light when you are performing
calculations in Stata."


Hi David:

Try increasing your memory incrementally using a program like the one described here:
  http://www.stata.com/statalist/archive/2009-07/msg00899.html

Try this with virtual memory turned ON and then try it again with it turned OFF & look for any differences in both the -query- in Stata as well as the memory usage reported in the Mac OSX 'Activity Monitor.app' ( located here: "/Applications/Utilities/Activity\ Monitor.app" ) because Stata might think it has more memory allocated than the system is really giving it. The reason for this is that *nix systems have virtually unlimited swap file space & it can also use mounted/storage/network drives or devices for swap space in parallel. So, even if VM is turned off in Stata, the system can readily use HD space for virtual memory AND if you've got an external HD or mounted network drive, your system mightbe using that to increase the memory that Stata can utilize. You can try this process again after disabling the Mac OSX virtual memory/swap space by editing your "/etc/rc" file (with caution): 1.typing into terminal: sudo pico /etc/rc 2. Type # in front of the line : "dynamic_pager -F ${swapdir}/swapfile" 3. now type into terminal: sudo srm /private/var/vm/swapfile* But I would make a backup of your swapfile* before tinkering with these settings (e.g. "sudo cp /etc/rc /etc/rc.orig" ).Another suggestion might be to find or create a dataset larger than your physical memory limits (4 GB) and ask Stata to open it--then take a look at your -query- and your 'Activity Monitor.app' (that is, if Stata will somehow open a file that large with VM turned off..)
Best, Eric

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